1. Field of the Invention
The present invention relates to a memory element and a memory device with which information (data) is written or erased in accordance with a change in the electrical property of a memory layer including an ion source layer.
2. Description of the Related Art
Examples of a well-known memory device used in information technology device such as a computer include not only a DRAM (Dynamic Random Access memory), which is a memory with high-speed and high-density operation but also non-volatile memory such as a flash memory, FeRAM (Ferroelectric Random Access Memory), and MRAM (Magnetoresistive Random Access Memory). Such memories makes it possible to retain stored data for a long time without power supply, but there are some merits and demerits respectively. As for the flash memory, its integration degree is high while its operation speed is not so fast. In the case of FeRAM, there is a limit of mirofabrication necessary for higher integration and there is also a disadvantage in its fabrication process. MRAM has a disadvantage in its power consumption.
Accordingly, a memory element of a new type, which is advantageous in particular to the limit of mirofabrication of a memory device, has been proposed. The memory device is configured in such a manner that an ion conductor containing a specific metal is sandwiched between two electrodes. The memory element is configured so that one of the two electrodes includes the metal contained in the ion conductor, therefore, when voltage is applied across the two electrodes, the metal contained in the electrode is diffused as an ion into the ion conductor so that electrical properties such as the resistance of the ion conductor and capacitance are changed. For example, Japanese Patent Publication No. 2002-536840 and Nikkei Electronics 20 Jan. 2003 (page 104) disclose a memory device in which the above-mentioned characteristics are used. In particular, Japanese Patent Publication No. 2002-536840 proposes an ionic conductor of a solid solution constituted from a chalcogenide and a metal.